1. Field of the Invention
The present invention relates to a light emitting device and a method of manufacturing the same, and more particularly, to a light emitting device and a method of manufacturing the same, which enhance light efficiency and reduce the manufacturing cost.
2. Discussion of the Related Art
As thin film growth technology is advanced and a light emitting material having good efficiency is developed, the application of a light emitting device including a light emitting diode (LED) is being expanded to a transmission module of an optical communication means, a backlight of a liquid crystal display (LCD) device, a lighting device capable of replacing a fluorescent lamp or an incandescent lamp, and a traffic light.
LEDs use the principle that when a voltage is applied between an anode and a cathode from an external circuit, a positive hole and an electron are injected into the anode and a cathode, the positive hole and the electron are recombined with each other in an active layer which is formed between the anode and the cathode to convert spare energy into light, and the light is emitted to the outside.
Light emitting devices including the LEDs has a structure (a package on board (POB) structure) in which an LED package is coupled to a printed circuit board (PCB), and is supplied with a current from the PCB connected to an external power source to emit light.
Hereinafter, a related art direct type backlight unit using an LED as a backlight and a related art LED package will be described with reference to the drawing.
FIG. 1 is a schematic cross-sectional view illustrating a structure of a related art direct type backlight unit for LCD devices, and FIG. 2 is a schematic cross-sectional view illustrating a related art LED package included in the related art direct type backlight unit for LCD devices.
With reference to FIG. 1, the related art direct type backlight unit for LCD devices includes an optical sheet 70, a diffusive plate 60, a light source LS, and a reflector 20 which are sequentially arranged under a liquid crystal panel 80. The direct type backlight unit is disposed in a cover bottom 10. Also, the light source LS includes an LED package 30 and a diffractive lens 50. In particular, a plurality of slit patterns 40 are provided at an inner surface or an outer surface of the diffractive lens 50.
Here, although not shown, the liquid crystal panel 80 includes a thin film transistor (TFT) array substrate and a color filter substrate, which are coupled to each other to maintain a uniform cell gap, and a liquid crystal layer which is formed by injecting liquid crystal therebetween.
The diffusive plate 60 diffuses light emitted from the light source LS.
Although not shown, the optical sheet 70 includes a prism sheet, including a lower prism sheet and an upper prism sheet which are used for the purpose of refracting light diffused by the diffusive plate 60 to increase a front luminance of the light, and a protective sheet that protects the prism sheet.
The LED package 30 is provided on the PCB 20 to emit light. The reflector 40 reflects the light, emitted from the LED package 30, to the diffusive plate 60.
The diffractive lens 50 is used to broaden a coverage of the light emitted from the LED package 30.
With reference to FIG. 2, the LED package 30 includes an LED chip 31, a first lead frame 33, a second lead frame 35, a molding part 37, and an encapsulating part 39.
The first lead frame 33 and the second lead frame 35 are electrically connected to a first electrode and a second electrode of a PCB (not shown).
The molding part 37 supports the first and second lead frames 33 and 35.
The encapsulating part 39 is formed of a light-transmitting resin in an open area which is formed on the molding part 37.
The related art direct type backlight unit and the related art LED package have the following problems.
First, the related art direct type backlight unit should use the diffractive lens 50 covering the LED package 30 so as to broaden a light-oriented angle, and whenever a structure of the LED package 30 is changed, the diffractive lens 50 should also be changed.
Second, since the related art direct type backlight unit uses the diffractive lens 50 so as to broaden a coverage of light, an optical gap O/G equal to or greater than a thickness of the diffractive lens 50 occurs, and for this reason, a thickness of an LCD module becomes thicker.
Third, among the LED chip 31, the first lead frame 33, the second lead frame 35, the molding part 37, and the encapsulating part 39 which are included in the related art LED package 30, structures of the first and second lead frames 31 and 33 are changed depending on a characteristic of the LED chip 31, and thus, a shape of the molding part 37 should be changed. For this reason, a reliability of the LEC package 30 is reduced, and the development cost and the manufacturing cost increase.